When officers arrived, they found 13-year-old Guzman DeJesus unresponsive and a bullet casing nearby, according to police reports. Howe then voluntarily gave officers a .40-caliber S&W Taurus pistol he had in his backpack.

Documents showed Howe brought the pistol to school for two months prior to the shooting, often allowing others to handle it.

Police have said since the shooting that Howe accidentally shot and killed Guzman DeJesus when he took the pistol out of his backpack and showed it off to others riding the bus.

In an exclusive interview with Local 10, a boy named "P.R." in police reports said he witnessed the shooting on Nov. 20, 2012. He said Howe brought the gun onto the bus but Guzman DeJesus shot herself, adding that she was handling the gun when it went off.

"The projectile path is from front to back, left to right and downward," says the medical examiner report.

Howe was sitting across the aisle from Guzman DeJesus and behind her, according to police diagrams. P.R. was sitting across the aisle from Howe and behind Lourdes.

Ron Book, the attorney representing Lourdes Guzman's family, said P.R.'s account to Local 10 was untrue.

"To go on the air, and try to tell this community that the young girl shot herself? There is not a scintilla of evidence that has been disclosed in discovery," Book said. "He duped this community. It's just wrong. It's offensive."